Moisture distribution system



May 19, 1970 A. L. WHEAR MOISTURE DISTRIBUTION SYSTEM Filed July 21,1967 2 Sheets-Sheet 1 INVENTOR May 19, 1970 T A; 1.. WHEAR 3,512,353

MOISTURE DISTRIBUTION SYSTEM Filed July 21, 1967 I 2 Sheets-Sheet 2 441260 A. WHEAZ pe Zi INVENTOR 5 2m waiw United States Patent 3,512,363MOISTURE DISTRIBUTION SYSTEM Alfred L. Whear, Minden, Nev. 89423 FiledJuly 21, 1967, Ser. No. 655,152 Int. Cl. E02b 13/00 US. CI. 61-13 21Claims ABSTRACT OF THE DISCLOSURE Liquid flowing through a distributiontube in a given axial direction is discharged through relatively smallbores in the wall of the tube with the bores directed contrary to theaxial direction at an angle of 6 to 14 from the axis of the tube. Theliquid may be under high pressure for atomized discharge or withoutpressure in a tube for subterranean irrigation.

BACKGROUND OF THE INVENTION In a system supplied with water atsubstantial pressure for fire prevention in a given region and again ina moisture distribution system operated at substantial pressure .l'orhumidifying the ambient atmosphere in a given region, there is need fornumerous outlet ports of inexpensive construction that provide atomizeddischarge and do so with substantially uniform or balanced moistureddistribution over the entire region. Outlet fittings or nozzles ofvarious forms are presently available for this purpose. In manyinstances such nozzles are inefficient atomizers; in other instances theatomizers are of relatively expensive construction to run up the cost ofinstallation; and, in many instances balanced or uniform distribution isachieved only by special and usually expensive provisions to compensatefor pressure drop in the system.

On the other hand, in an underground irrigation system for supplyingwater to a given area there is need for an automatic moisture-responsivecontrol to operate the system periodically in accord with the moisturedemand of the soil. There is also need in such an irrigation system forhighly economical corrosion-resistant piping and need for non-cloggingdistribution outlets of efiicient but inexpensive construction. There isfurther need for aeration of the soil by the irrigation system togetherwith a need for suitably retarded flow at each outlet to avoid anysignificant degree of underground erosion. Finally, there is a specialneed for uniform water distribution among the numerous outlets to avoideither an oversupply or an undersupply in any part of the ground area.

SUMMARY OF THE INVENTION A basic discovery underlying the invention isthat a relatively long distribution tube having numerous longitudinallyspaced outlet bores in its wall will meet the requirements for widelydifferent purposes and widely ditferent modes of operation provided thatthe outlet bores are inclined upstream at an angle of 6 to 14 relativeto the axis of the tube and further provided that the tube wall issufficiently thick to make the bores long enough for directional elfect,i.e., to cause the discharge at each bore to be in a general directionopposite to the direction of flow through the tube.

In a fire prevention sprinkler system or in a system for humidifying theatmosphere water is supplied to the distribution tubes at substantialpressure, say at a pressure of 25 to 150 p.s.i., and the water isatomized or reduced to finely divided form as it issues from each outletbore. At the other extreme, a similar distribution tube in asubterranean irrigation system is supplied with water at extremely lowpressure and at an extremely low rate to seep through each outlet boreat a rate measured 3,512,363 Patented May 19, 1970 in drops per secondin a substantially non-clogging manner.

In a subterranean irrigation system incorporating the invention, adistribution tube is called a seep tube and a manifold, which may besubstantial level, supplies branch seep tubes that are spaced, saytwelve inches apart, on each side of the seep tube with the seep tubeson the two sides of the manifold staggered. Each seep tube is downwardlyinclined, say at a drop of approximately one foot for every fifty feetof length, for gravity flow through the seep tube. The supply flow intothe manifold is throttled to a relatively low rate so that when thesystem is in operation the manifold is filled to approximately 60%capacity and the flow into the manifold is just suflicient to maintaingravity flow in the various seep tubes. Thus, the exceedingly low rateof seepage from the spaced seep tube outlets at least approximatelymatches the percolation rate of the soil and the rate at which themanifold supplies the various seep tubes matches the demands of the seeptubes for gravitational flow therethrough.

In practice, the rate of inflow into a manifold may be determined by atemporary standpipe. For this purpose a tube of clear plastic isconnected to the downstream end of the manifold preferably on theunderside of the manifold and the tube is turned upwardly forobservation of the water level therein. With the manifold in operationthe rate of supply flow is throttled or adjusted as required to causethe water level in the upwardly extending tube to be at approximatelyground level. For shallow irrigation, for example, to supply Water tothe turf of a golf course, the seep tubes maybe buried at three andone-half inches to four inches below ground level, whereas for deeperirrigation in an orchard the seep tubes may be buried at a depth ofsixteen inches to twenty inches. In either case, the pressure isadjusted in the manifold to cause the water level in the upright tube toreach approximately ground level. The higher pressure in the deeperburied manifold compensates for the fact that the resistance to flowinto the soil is greater at the greater depth. After a tube has servedits temporary'purpose as a standpipe, it may be cut short, plugged atthe end, and buried in the soil.

An important feature of the invention is that at the contemplatedextremely low rates of subterranean discharge, the fines in the soilwhich are the primary source of food for plant life are not disturbed toany significant extent, i.e., no significant degree of subterraneanerosion occurs. The contemplated rates of flow are in the range of oneto five gallons per square foot per hour. In a given subterraneanirrigation system where the seep tubes are spaced twelve inches apart inparallel relation and the reversely directed outlet bores are spaced sixinches apart along the length of each seep tube, the rate of flow may bein the range of one to five drops per second at each outlet bore.

Another important feature of the invention is the aeration of the soilby the irrigation system. When the irrigation system is idle both thesupply pipe and the manifolds that branch therefrom may be empty ornearly empty of water to provide an initial volume of air which is to bedisplaced into the soil when the irrigation system is again placed inoperation. In addition, there is a useful degree of aeration of thewater that is inherent in the operation of the system.

A further advantage of the invention is that it may be employed toeradicate insect pests from badly infected soil to make possible theraising of crops which otherwise would be prohibited by the infestation.For this purpose an irrigation system embodying the invention isinstalled in an infested plot of ground and then a gaseous fumigant isintroduced into the irrigation system for distribution thereby. Thegaseous fumigant selected for this purpose is capable of completedissipation from the soil within two or three days. After a time periodto permit thorough dissipation of the fumigant the crop is planted andthe irrigation system is placed into operation to keep the soil suppliedwith moisture.

A further important feature of the preferred practice of the inventionis automatic periodic irrigation with provision for varying the durationof both the periods of irrigation and the intervals between theirrigation periods. For this purpose a suitable moisture-sensing meansis buried in the soil to initiate an irrigation operation in response todrop to a predetermined degree of the moisture content of the soil. Whenthe soil is dry enough to cause the moisture-sensing means to startwater flow, the newly released moisture migrates to the sensing meansfrom the seep tube that is nearest to the sensing means and, of course,the resulting period of irrigation continues until the supplied moisturereaches the sensing means to cause the sensing means to cut off waterflow.

It is apparent that the duration of a periodic irrigation operationvaries with the distance of the sensing means from the nearest seep tubeand, since the amount of water that is introduced into the soil varieswith the duration of the irrigation period, the time that is requiredfor the soil to again dry out also varies with the distance of thesensor from the nearest seep tube. Thus, both the duration of theperiodic irrigation operations and the frequency of the periodicirrigation operations may be varied simply by varying the distancebetween the sensing means and the nearest seep tube.

In both a high pressure atomizing system and a low pressure irrigationsystem, balanced distribution is desirable in the sense of uniform ratesof flow among the numerous reversely directed outlets and substantiallysimultaneous initiation and cessation of flow at all of the outlets. Inpractice, such balanced flow requires that when operation of the systemis initiated, the main supply pipe downstream from the master valve fillsubstantially to capacity before water is delivered to any of themanifolds that branch from the supply pipe and it is further requiredthat each manifold fill to capacity before any substantial amount ofwater is discharged into any of the numerous distribution tubes thatbranch from the manifold. Finally, each distribution tube should fill tocapacity before water is discharged from any of the distribution outletbores. Thus, in the operation of such a balanced system there is aninitial delay for the supply pipe to fill and then a further delay forthe manifolds to fill before flow is started in the various distributiontubes. Thereafter, the discharge from the reversely directed outlets ofthe distribution tubes is substantially uniform along the length of eachtube.

In both a high pressure atomizing system and a low pressure irrigationsystem, the desired initial delay in flow from a main supply pipe intoits branching manifolds is accomplished by providing each manifold witha special inlet fitting that projects into the interior of the supplypipe. Each of these inlet fittings has an inlet opening which facesdownstream of the main supply pipe.

In such an arrangement initial flow past each inlet fitting occurs atrelatively high velocity and causes lowering of pressure, i.e., createsa suction effect at the inlet fitting which effect discourages outflowthrough the inlet fitting to the corresponding manifold. The reversepressure differential or suction effect which discourages outflowthrough the various inlet fittings is only temporary because when thesupply pipe becomes filled substantially to capacity, the flow velocityin the supply pipe drops to terminate the reverse pressure differentialor suction effect and thereby permit flow to start in all of themanifolds substantially simultaneously.

To control the flow from each manifold into the numerous distributiontubes that branch therefrom, each of the distribution tubes is providedwith the same type of inlet fitting, the inlet fitting projecting intothe interior of the manifold and having an inlet opening facingdownstream of the manifold. Here again, the various inlet fittingsresist outflow therethrough until the manifold is filled substantiallyto capacity whereupon outflow is initiated nearly simultaneously throughthe various distribution tubes.

As heretofore stated, the distribution tubes that are employed in a highpressure atomizing system may be of the same construction as the seeptubes employed in a low pressure subterranean irrigation system. Asurprising fact is that under the two widely different operatingconditions the release of fluid is substantially uniform along thelength of a distribution tube.

In a high pressure atomizing system the phenomenon of equalized outletflow along the length of a distribution tube is complex and apparentlyis the result of conflicting factors. One factor, of course, is that inany conduit having numerous outlets spaced along its length the pressureprogressively drops along its length, and if pressure alone were theonly factor more water would be released from the outlets at theupstream end of the conduit than at the downstream end. An opposingfactor, however, in a high pressure atomizing system is that each of thereversely directed outlet bores of a distribution tube tends to set up aflow-resisting reverse pressure differential or suction effect. Sincethe tendency to create a reverse pressure differential or suction effectvaries with the velocity of flow through the tube and since the velocityprogressively lowers along the length of the tube, both the flowpromoting effect and the flow resisting effect drop progressively alongthe length of the tube and apparently the difference between the twoeffects is substantially constant along the length of the tube to resultin the desired uniform rate of outflow.

Apparently, additional factors also oppose the flow promoting effect ofthe Water pressure at the outlet bores of a distribution tube in a highpressure system. One of these additional factors is that since theoutlet bores of the distribution tube are inclined upstream, thedirection of outflow is locally reversed and the momentum of the flowingwater in the tube makes it difficult for the change in direction tooccur. This conflict inherent in the change of direction of flow createsrelatively violent turbulence at the inlet end of each of the outlets.Another additional factor is that turbulence is further promoted by theimpingement of the stream in the tube against the inclined shoulder thatis formed by each of the reversely directed outlet bores. It is theseopposing factors that account for the atomized discharge from thereversely directed outlets of a distribution tube in a high pressuresystem. Thus, the invention teaches a new means for automized dischargeof water.

Turning now to a low pressure subterranean irrigation system, theoutflow from the same type of distribution tube is also balanced in thesense that the water discharge among the numerous outlets along thelength of a seep tube is substantially uniform. In this instance,however, the balanced flow is accounted for by the fact that the waterpressure and the rate of flow are so low that there is very littlepressure drop along the length of a seep tube.

In a subterranean irrigation system where outflow at such a gradual rateoccurs at numerous outlet ports of small cross section, a problem arisesin that it is impossible to avoid the entrainment of sand particles andother particles in the system and such particles tend to clog up thesmall diameter outlet bores. Fortunately, the reversely directed outletbores discourage clogging because, in the first place, the abruptreversal in the direction of flow tends to eject entrained particlesback into the main stream and, in the second place, the impingement ofthe flowing water on the previously described inclined shoulders at theinlet ends of the bores prevents any accumulation of particles at theshoulders. Any particle that approaches such a shoulder is diverted intothe main stream by the sweeping action. As a result, a subterranean seeptube will function over a long service period without any significanttendency for its outlet bores to become clogged.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic view of amoisture distribution system wherein a plurality of spaced distributiontubes branch from a common manifold, the view representing either a highperssure atomization system or a low pressure subterranean irrigationsystem;

FIG. 2 is an enlarged cross section of the manifold taken along the line22 of FIG. 1 showing various inlet fittings projecting from thedistribution tubes into the interior of the manifold;

FIG. 3 is a fragmentary longitudinal section along the line 33 of FIG. 2showing one of the inlet fittings;

FIG. 4 is a section along the line 4-4 of FIG. 2 showing how each of theinlet fittings may be provided with an exterior flange that indicatesthe orientation of the fitting and also indicates the direction of flowthrough the manifold;

FIG. 5 is a greatly enlarged longitudinal sectional view of adistribution tube showing the reversel directed bores that constitutethe outlets of the distribution tube;

FIG. 6 is a diagrammatic plan view of a subterranean irrigation system,part of the system being employed for underground irrigation of a lawnor turf and another part of the system being employed for subterraneanirrigation of rows of trees;

FIG. 7 is an enlarged section along the line 7-7 of FIG. 6 showing howan inlet fitting of each manifold projects into the interior of the mainsupply pipe;

FIG. 8 is an enlarged fragmentary longitudinal section of a manifoldshowing how a flexible plastic tube may be employed for drainage of themanifold between periods of operation of the system; and

FIG. 9 is a schematic view showing how a buried moisture-sensing meansmay control the pilot valve of a master control valve for periodicoperation of an irrigation system.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIGS. 1 through 5 show theessential structure of a moisture distribution system which may beeither a high pressure atomizing system or a low pressure subterraneanirrigation system.

FIG. 1 shows a single manifold 10 with numerous lateral distributiontubes 12. The manifold 10 may be made of a suitable plastic such aspolyvinylchloride and the distribution tubes may be made of a suitableplastic such as a polyethylene. The manifold 10 is supplied with waterfrom a pressurized source by a master valve 14 which may have a suitablecontrol 15. The rate at which the water enters the manifold 10 may bevaried by manual adjustment of a choke valve 16 but the choke valve maybe omitted if the master valve 14 incorporates an adjustment for thispurpose.

The control may take various forms in various systems. For example, thecontrol 15 may be simply a handle for manual operation of the mastervalve or may be a push button for electrical actuation of the mastervalve by remote control. For a fire prevention system, the control 15may be a thermally responsive means such as a thermostat or a controlutilizing a low melting material in a well known manner. For ahumidifying system the control 15 may incorporate a suitable humiditydetector. If the system is a low pressure subterranean irrigationsystem, the control 15 may incorporate a suitable moisture sensor aswill be explained hereafter.

The simplified system shown in FIG. 1 has a single manifold 10 withprovision for balanced flow to the various branching distribution tubes12. In a more elaborate system having a number of manifolds 10 branchingfrom a common supply pipe, provision would be made for balanced flow tothe various manifolds as 6 will be explained hereafter. The distributiontubes 12 are spaced apart in accord with the particular purpose of thesystem and while the distribution tubes are shown as parallel they arenot necessarily parallel.

Each distribution tube 12 has numerous outlets 18 which, as shown inFIG. 5, are bores in the wall of the tube with each bore inclinedupstream towards its outer end at an angle to the axis of the tubewithin the range of 6 to 14. An angle of approximately 10 is preferred.It will be noted in FIG. 5 that each inclined outlet bore forms asloping shoulder 20 inside the distribution tube which shoulder isexposed to the flowing stream of water.

The outlet bores 18 may be at any desired spacing along the length ofthe distribution tube, for example, a spacing of six inches, suchspacing for any given installation being within the skill expected inthe art. If desired, groups of the outlet bores may be spaced apart sixinches longitudinally of the tube with the bores in each group spacedapart circumferentially of the tube.

The inside diameter of a distribution tube 12 will vary with the lengthof the tube. For example, a distribution tube fifty feet long may havean inside diameter of inch with a wall thickness of inch and thediameter of the outlet bores may be .021 inch. With a tube wall of thestated thickness and with an outlet bore of the specified diameter andwith the outlet bore inclined approximately 10", the length of theoutlet bore will be several times its thickness so that the outlet borewill have a definite directional effect. The directional effect isimportant because it is contemplated that liquid may escape through anoutlet bore only by reversing its direction with respect to thedirection of main flow through the tube.

To achieve balanced initiation of flow among the various distributiontubes 12, each distribution tube is provided with an inlet fitting 22which may be made of a suitable plastic. As shown in FIGS. 2 and 3, eachinlet fitting 22 is of tubular configuration and may be cemented into acorresponding radial bore in the tube wall. In the construction shown,each inlet fitting 22 is provided with a radial flange 24 which abutsthe outer surface of the tube and serves as a stop to determine theextent to which the fitting protrudes into the interior of the manifold10. Each of the tubular inlet fittings 22 is cut off at an acute angleas indicated in FIG. 3 to provide an elliptical inlet opening 25 as maybe seen in FIG. 2 and the inlet fitting is so oriented that theelliptical inlet opening faces downstream.

A feature of the invention is that the radial flange 24 of an inletfitting 22 not only serves as a stop when the inlet fitting is beinginstalled in a manifold 10, but also serves as means to indicate theorientation of the inlet fitting. For this purpose the radial flange 24is formed with a point 26 as shown in FIG. 4, the point indicating thedirection in which the inlet opening faces. The pointed flange not onlyprovides guidance for orientation of an inlet fitting in a manifold 10,but also provides guidance in the orientation of a manifold in a system.

As heretofore noted, it is preferred that a manifold 10 be at leastnearly empty when the system is not in operation. With a manifold nearlyempty, initial flow through the manifold is relatively rapid but thepressure in the manifold does not rise until the manifold is filled toits normal capacity. It is this preliminary delay period that providesbalanced starting fiow in the sense that outflow starts through all ofthe distribution tubes substantially simultaneously.

In a high pressure atomization system a manifold 10 fills rapidly andfills completely with water. On the other hand, in a low pressuresubterranean irrigation system the inflow to the manifold is throttledand the manifold fills with water to less than its full capacity, say to60% of its full capacity. Since the Water level in a low pressure systemdoes not reach the top of the manifold, the various seep tube inletfittings in the manifold are at relatively 7 low levels, no seep tubeinlet fitting being mounted on the top side of the manifold.

The preliminary delay required for balanced fiow occurs in a lowpressure manifold in substantially the same manner as in a high pressuremanifold, but the prelim= inary delay is longer. During this initialperiod in which the water flows along the manifold at substantialvelocity but without appreciable pressure, the force of the water pastthe inlet fittings 22 creates a partial vacuum on the downstream side ofeach inlet fitting and consequently the tendency is for air to be drawninto the manifold through the inlet fittings of the seep tubes insteadof water being forced into the seep tubes. When the manifold fills toits capacity, however, pressure'rises in the manifold and overcomes thevacuum effects at the various inlet fittings to cause flow to beinitiated into the various seep tubes.

When water flow into the seep tube is initiated, the same kind of delayoccurs because a mild resistance to outflow exists at each of thedischarge bores of the seep tube because of the reverse direction of theoutlet bores. As soon as a seep tube fills completely with water,however, the resultant mild pressure rise causes substantialsimultaneous initiation of outflow at each of the outlet bores.

FIG. 6 shows diagrammatically a low pressure subterranean irrigationsystem which includes a supply pipe 30 with a number of manifoldsbranching therefrom. One manifold 10a irrigates a lawn or turf area andfor this purpose has parallel lateral seep tubes 12a spaced twelveinches apart and buried in the soil at a depth of three and one-halfinches to four inches at the inlet ends of the seep tubes. Each of theseep tubes 12a may be horizontal but preferably slopes downwardlytowards its outer end as heretofore stated. Two manifolds 105 shown inFIG. 6 are employed for subterranean irrigation of rows of trees 34 andfor this purpose the corresponding seep tubes 12b are looped around eachtree at a depth of sixteen inches to twenty inches below ground level.

FIG. 6 shows diagrammatically a master valve 35 with a choke valve 36downstream therefrom, but the choke valve may be omitted if the mastervalve incorporates flow adustment means. In a well known manner themaster valve 35 includes a pilot tube 37 controlled by a pilot valve,which pilot valve is incorporated in a moisture sensor 38 that is buriedin the soil. In this instance it is assumed that the water source is ata pressure above 40 p.s.i. and, therefore, it is desirable to place apressure reducer 40 in the pilot tube 37 between the master valve andthe moisture sensor to reduce the water pressure in the pilot tube atthe moisture sensor. Preferably, the pilot tube 37 extends beyond themoisture sensor 38, as shown, and empties into the supply pipe 30.

FIG. 9 shows how the choke valve 36 may be omitted by incorporating itsfunction in the master control valve. In FIG. 9 the master control valve35 which is connected to a pressurized water source is in turn connectedby a pipe 45 to the previously mentioned supply pipe 30.

The master control valve 35 has a diaphragm 48 which carries a volvemember 50 for cooperation with a valve seat 52. A manual adjustmentscrew 54 limits the extent to which the valve member may retract fromthe valve. seat and thus serves the purpose of a manually adjustablethrottle valve.

The diaphragm 48 forms a control chamber 55 and the valve member 50 hasa bleed aperture 56 for communication with the control chamber. Thepreviously mentioned pilot tube 37 extends from the control chamber 55to the pilot valve that is incorporated in the moisture sensor 38. Thepilot valve in the moisture sensor has a valve seat 62 and a cooperatnigvalve member 64 that is controlled by a block 65 of fibrous material.

When the block 65 becomes relatively dry it contracts longitudinally toretract the valve member 64 from the valve seat 62 to permit flowthrough the pilot tube 37. On the other hand, when the block 65 becomessoaked with moisture it expands to seat the pilot valve member.Normally, both the master control valve 35 and the pilot valve areclosed with the control chamber 55 at line pressure. Whenever the pilotvalve opens, the consequent drop in pressure in the control chamber 55causes the diaphragm to retract the valve member 50 from the valve seat52.

As heretofore pointed out, the frequency of the operation of thesubterranean irrigation system shown in FIG. 6 and the duration of theperiods of operation depend upon the distance that the moisture sensor38 is placed from the nearest seep tube. The pilot tube 37 empties intothe supply pipe 46 because if it were to empty into the soil it wouldsupply moisture in the region of the moisture sensor and thus defeat thepurpose of the moisture sensor.

The manner has already been described in which inlet fittings 22 areemployed at the inflow ends of seep tubes for balanced flow among theseep tubes that branch from a manifold. In the same manner, similarinlet fittings project from the manifolds 10 in FIG. 6 into the supplypipe 30 for balanced flow among the various monifolds. FIG. 7 shows howthe end portion 66 of a manifold 10 may project into the supply pipe 30.In a manner heretofore described, the end portion 66 of the manifold iscut off at an angle to provide an elliptical inlet port 68 that facesdownstream in the supply pipe.

A certain problem arises in that it is desirable to provide some meansfor draining a manifold at the end of an irrigation period. One way toobtain such rainage is to mount one of the seep tubes on the undersideof the manifold to provide a drainage passage. Thus, FIG. 2 shows aninlet fitting 22a that is low enough in the manifold 10 to serve asdrainage means.

FIG. 8 shows an alternate drainage means that may be employed either ina manifold or in a supply pipe. In FIG. 8 the manifold or supply pipehas a drainage port which is occupied by a short flexible drainage tube70. In the absence of water flc-w against the side of the drainage tube70, the drainage tube assumes an upright position as indicated by solidlines and water freely gravitates through the drainage tube. When thesystem is in operation, however, the dynamic pressure of the flowingwater bends the tube as shown in dotted lines to such an extent as tokink the tube and thereby cut off drainage communication through thetube.

My description in specific detail of the presently preferred practicesof the invention will suggest various substitutions, changes and otherdepartures from my disclosure within the spirit and scope of theappended claims.

1. In a system for distributing a liquid to spaced points in a givenregion the combination of:

a conduit extending into the given region;

means to supply the liquid to the conduit for flow therethrough in agiven longitudinal direction, said conduit having a plurality of spacedperipheral discharge passages,

each of said discharge passages being of a length substantially greaterthan its cross dimension for directional effect on the flowtherethrough,

each of said discharge passages being directed contrary to said givendirection at an angle to the axis of the conduit in the range of 6 to14.

2. A combination as set forth in claim 1 in which said angle isapproximately 10.

3. A combination as set forth in claim 1 in which said dischargepassages are bores in the wall of the conduit.

4. A combination as set forth in claim 1 in which said given region isin an atmosphere and said supply means supplies the liquid to theconduit at a substantial pressure to cause atomization into theatmosphere of the liquid from the discharge passages because of thecontrary direction of the discharge passages.

5. A combination as set forth in claim 1:

in which said system is an irrigation system;

in which said given region is below ground level; and

in which said supply means supplies water to the conduit at relativelylow pressure to cause the rate of discharge of the water from thedischarge passages to be low enough to avoid significant disturbance ofthe soil structure.

6. A combination as set forth in claim 5 in which said conduit isinclined downwardly in said given direction; and

in which said supply means supplies water to the upper end of theconduit at low pressure and at a low rate for low velocity free gravityflow through the conduit as distinguished from high velocity flowcreated by a substantial pressure differential.

7. A combination as set forth in claim 1 which includes a manifoldconnected to said supply means;

in which said conduit is one of a plurality of conduits branching fromsaid manifold at spaced points along the length of the manifolds; inwhich each of said conduits has an inlet fitting projecting into theinterior of the manifold; and I in which said inlet fittings have inletopenings facing downstream with respect to said given longitudinaldirection whereby reduction of pressure at the inlet fittings caused byflow of the liquid past the inlet openings substantially retards flowfrom the manifold into the respective conduits until initial flow intothe manifold accumulates sufficient liquid in the manifold to cause asubstantial drop in the velocity of flow through the manifold.

8. A combination as set forth in claim 7 which includes means on theexterior of the manifold to indicate the directions in which saidopenings of the fittings face for guidance in the installation of thefittings in the manlfold as well as for guidance in the installation ofthe man fold with respect to the direction of flow through the manifold.

9. A combination as set forth in claim 1 in which:

said system is a subterranean irrigation system; said system includes asubterranean manifold connected to said supply means;

said conduit is one of a plurality of conduits branching from saidmanifold at spaced points along the length of the manifold; and

the pressure in the manifold is substantially equal to a head of waterextending from the manifold to approximately ground level.

10. A combination as set forth in claim 9 in which the conduit issubstantially horizontal.

11. In an irrigation system, the combination of:

a subterranean conduit for water flow therethrough in a givenlongitudinal direction,

said conduit having a plurality of spaced discharge passa es,

each of said discharge passage being directed contrary to said givendirection at an a cute angle to the axis of the conduit where'by waterflowing through the conduit sweeps across the inlet of each dischargepassage and impinges on an inclined shoulder formed by the inlet on thedownstream side thereof to tend to carry entrained particles past theinlet and to tend to sweep away any particles that reach the inclinedshoulder, thereby to minimize clogging of the discharge passages =byentrained particles; and

means to supply water to said conduit at a rate low enough to avoid anysignificant erosion of the soil in the regions of the dischargepassages.

12. A combination as set forth in claim 11 in which the means to supplywater to the conduit supplies the water at a rate equivalent to one tofive gallons per hour per square foot of the irrigated area.

13. A combination as set forth in claim 11 in which said dischargepassages are bores in the wall of the conduit, each bore being of-alength substantially greater than its diameter.

14. A combination as set forth in claim 111 in which said conduit isinclined downwardly from its inlet end for a drop not substantially morethan one foot for each fifty feet of length for free gravitational flowtherethrough at a given rate permitted by said discharge passages; and

in which said supply means supplies water to said conduit atsubstantially said given rate.

15. A combination as set forth in cairn 11 which includes moistureresponsive means buried inthe soil near said conduit to control flow ofwater into the conduit and to initiate such flow in response to apredetermined drop in moisture at the responsive means, thereby to causeperiodic irrigation of the soil,

the frequency of the periods of irrigation depending upon the durationsof the periods of irrigation and the duration of the periods ofirrigation depending, in turn, on th elength of time required for waterto migrate through the soil from the conduit to the responsive means,

whereby both the frequency and the duration of the irrigation periodsmay be varied by varying the distance of the moisture responsive meansfrom the.

conduit.

16. In an irrigation system, the combination of:

at least one manifold;

a plurality of subterranean distribution conduits branching from themanifold at spaced points thereof, each of said conduits having spaceddischarge ports, said conduits being downwardly inclined towards theirouter ends for gravity flow therethrough;

a plurality of inlet fitting at the inlet ends of said conduiltsprojecting into the interior of the manifold; an

means to supply water periodically to said manifold at a rate for freerunning gravity flow through the plurality of conduits at notsubstantially more than one p .s.i.,

each of said inlet fittings having an inlet opening in the manifoldfacing downstream thereof whereby reduction of pressure at each of theinlet openings caused by flow of the water past the inlet openingsubstantially retards flow from the manifold through the respectiveconduits until initial flow into the manifold accumulates suflicientwater in the manifold to cause a substantial drop in the velocity offiow through the manifold.

17. A combination as set forth in claim 16 in which said means to supplywater periodically to the manifold includes a control means including apilot valve;

which includes moisture-responsive means buried in the the soil tooperate said pilot valve;

and which includes a tube to deliver the water from the pilot valve tothe interior of the manifold to prevent the water that flows through thepilot valve from affecting the moisture-responsive means.

18. A combination as set forth in claim 16 in which each of said inletfittings is of the configuration of a tube with an inlet end of the tubecut off at an acute angle relative to the axis of the tube to form anelliptical inlet opening facing downstream of the manifold.

19. A combination as set forth in claim 16 in which at least one of theinlet fittings in the manifold is in the lower half of the manifold todrain liquid from the manifold between the periods in which water issupplied to the manifold.

20. A combination as set forth in claim 16 in which said manifold has adrainage port and in which a drainage tube projects into the manifoldfrom the drainage P said drainage tube being resiliently flexible toflex in response to flow of water through the manifold and thereby sealoff the drainage port as long as water is flowing through the manifold.

21. A combination as set forth in claim 16 in which:

a plurality of manifolds branch from a supply pipe With subterraneandistribution conduits branching from each manifold;

each of said manifolds has an inlet fitting projecting into the interiorof the supply pipe; and

each of said inlet fittings has an inlet opening in the supply pipefacing downstream therein,

whereby reduction of pressure at each of the inlet fittings in thesupply pipe caused by flow of water past the fitting substantiallyretards flows from the supply pipe into the respective manifolds untilinitial flow into the supply pipe accumulates sufficient water in thesupply pipe to cause a substantial drop in the velocity of flow in thesupply pipe.

1 2 References Cited UNITED STATES PATENTS 1,204,309 11/ 1916 Peterson239550 3,204,872 9/1965 Whear 6l13 X 3,302,323 2/1967 Popa 239-450 X3,361,363 l/1968 Babington 6l13 X FOREIGN PATENTS 844,498 4/1939 France.

